Field
The present disclosure relates generally to communication systems, and more particularly, to a Physical Random Access Channel (PRACH) in Narrow Band (NB) wireless communication.
Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to support mobile broadband access through improved spectral efficiency, lowered costs, and improved services using OFDMA on the downlink, SC-FDMA on the uplink, and multiple-input multiple-output (MIMO) antenna technology. However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in LTE technology. These improvements may also be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.
Narrow Band (NB) wireless communication, such as NB Internet of Things (NB-IOT), faces numerous challenges. It has a limited frequency dimension that may be shared by multiple users. For example, NB-IOT may occupy a single Resource Block (RB), which presents unique challenges for a NB PRACH. Large coverage areas, may result in for NB-IOT timing offsets that extend beyond the range for which the Normal Cyclic Prefix (NCP) can compensate. Furthermore, devices may face different environments based on device placements and installation locations.